Post-mastectomy pain syndrome (PMPS) and phantom breast pain are poorly understood chronic pain syndromes that occur following surgical procedures for breast cancer. Although these pain syndromes are not well studied, there is appreciable evidence that patients with PMPS or phantom breast pain can be significantly disabled by their chronic pain and can suffer from substantial reductions in quality of life. The primary aims of this research project are to identify risk factors for these chronic pain syndromes following surgical procedures for breast cancer, characterize their natural history, and examine their impact on quality of life using a prospective research design. To date, 40 women scheduled for surgical procedures for breast cancer have been assessed with respect to hypothesized risk factors for chronic pain. These women are now being studied for one year following their surgery, with periodic assessments of pain, health-related quality of life, and psychosocial variables. This allows risk factors for PMPS and phantom breast pain to be identified and the impact of chronic pain on quality of life to be determined. The pathogenesis of PMPS and phantom breast pain are unknown, and the identification of risk factors constitutes an important first step in understanding the processes by which chronic pain develops; this knowledge may lead to the development of more effective treatment approaches. By identifying risk factors, the results can also be used to design interventions aimed at preventing the development of chronic pain following surgical procedures for breast cancer. Moreover, the identification of risk factors will make it possible to determine which patients are most in need of such preventive efforts.